Seals are generally employed to prevent ingress of contamination and debris into spaces between moving parts of various machines and structures. For example, seals are employed to prevent the ingress of debris into a space between an inner member and an outer member of a bearing in which the inner member and/or outer member rotate and/or misalign relative to one another. One type of bearing is a track roller bearing that typically includes an inner member positioned for rotational movement in an outer race. The inner member defines an outer surface, and the outer race defines an inner surface. A plurality of rolling elements such as needle rollers are disposed in a cavity formed between the outer surface of the inner member and the inner surface of the outer race. Contamination of the rolling elements, the outer surface of the inner member and the inner surface of the outer race, is one of the leading causes of bearing damage. Typically, the track roller bearing assemblies includes a sealing arrangement on opposing sides thereof, wherein a seal has opposing ends disposed in a groove on each of the inner member and the outer race. The seal aids in retaining a lubricant, such as grease, between the cavity and for inhibiting the ingress of dirt, water, particulate matter, and other contaminants to the sliding engagement surfaces.
In some instances, the seal does not adequately retain the grease in the bearing. As a result, grease leaks out of the bearing contaminating adjacent structures and depleting the grease in the bearing. Such depletion of the grease can cause the bearing to prematurely fail. Accordingly, some bearings are provided with grease replenishment systems to periodically add grease to the bearing. For example, grease replenishment systems in track roller bearings typically include passages (e.g., holes) that extend through the inner member and communicate with the cavity and rolling elements between the inner member and the outer race via one or more grooves formed in the inner surface of the outer race and/or the outer surface of the inner member. Grease can be provided to the grease replenishment systems via manual hand held devices or via an automatic intermittent pressurized supply of grease. In some instances the replenishment of the grease disturbs the preferred configuration of the seal, which can result in seal failure and the leakage of grease from the bearing. In certain aircraft bearing applications, such as bearings located in leading or trailing control surfaces in aircraft wings, lubrication systems cannot be employed due to space and weight constraints.
Based on the foregoing, there is a need to provide a bearing with a seal that retains grease in the bearing over the entire life of the bearing and to prevent the bearing from being improperly charged with grease.